JP2529745B2 - Active noise control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active noise control device, and in particular, it generates control sound for noise transmitted from a plurality of noise sources, and interferes with each other. The present invention relates to a noise control device that reduces noise and is suitable for reducing noise in a vehicle cabin, an aircraft cabin, and the like.

[Conventional technology]

Conventionally, as an active noise damping device of this type, for example, a device described in British Patent Publication No. 2149614 is known. This conventional device is applied to an aircraft cabin or a similar closed space, and a single noise source such as an engine located outside the cabin generates sound including a fundamental frequency f ₀ and its harmonics f _{1 to} f _n. It operates under the condition that it does.
Specifically, the above-mentioned conventional device includes a plurality of loudspeakers (secondary sound sources) and microphones installed in a closed space, a frequency detection unit that detects frequencies f _{0 to} f _n of a noise source, and a plurality of microphones. A signal processor for supplying a plurality of loudspeakers with signals of opposite phases to the components of the detection frequencies f _{0 to} f _n based on the output signal of the loudspeaker and the detection signal of the frequency detection means. The secondary sound generated from the sound source and the primary sound transmitted from the noise source interfere with each other to minimize the sound pressure level in the closed space.

[Problems to be Solved by the Invention]

However, since the above-described conventional device is configured to reduce the noise in the closed space generated from a single noise source (primary sound source), for example, when noise is transmitted from multiple noise sources, It has been unsuitable for reducing the noise transmitted from a plurality of noise sources, for example, the noise reduction target related to the detection means must be applied to any noise source.

On the other hand, it is assumed that a plurality of conventional devices are mounted in parallel for a plurality of noise sources and each of them is independently driven.
In such a case, the device becomes large and complicated, and the residual noise at each observation point, that is, at each microphone installation position, is arbitrarily controlled by a plurality of individual systems. There was a problem that the control balance of the whole observation point deteriorated, such as the noise level greatly differed between the two.

The present invention was made by focusing on the problems of such a conventional device, and the problem to be solved is to eliminate the noise generated from these noise sources even when there are a plurality of noise sources. The most dominant noise source is selected and reduced according to the operating state of the power generation device at that time, and efficient and effective noise control is performed as a whole.

[Means for solving the problem]

In order to solve the above problem, in the invention according to claim (1), a control sound is generated from a control sound source in an acoustic space where noise is transmitted from a plurality of noise sources that are not correlated with each other to reduce the noise. In the active noise control device configured as described above, a plurality of noise generation state detection means for individually detecting signals relating to the noise generation state of the plurality of noise sources, and a detection signal of each of the plurality of noise generation state detection means And at least as many control sound sources as the control sound sources and individually input the detection signals, and control sound source driving means for adding the respective outputs of the plurality of adaptive filters for each control sound source and supplying the control sound sources. And a residual noise detecting means for detecting residual noise at an observation position in the acoustic space, an operating state determining means for determining an operating state, and the operating state A noise selection unit that selects the most dominant noise among the noises transmitted from the plurality of noise sources based on the determination result of the disconnection unit, and a noise generation state detection unit that corresponds to the noise selected by the noise selection unit. There is provided adaptive control means for controlling the adaptive filter so that the noise at the observation position is minimized based on the detection signal and the detection value of the residual noise detection means.

Further, in the invention according to claim (2), in an acoustic space where noise is transmitted from a plurality of noise sources having no correlation with each other,
In an active noise control device configured to generate a control sound from a control sound source to reduce the noise, a plurality of noise generation state detecting means for individually detecting signals relating to the noise generation state of the plurality of noise sources, and an operation A driving state judging means for judging the state, and a noise selecting means for selecting a detection signal corresponding to the most dominant noise from the detection signals of the plurality of noise generation state detecting means based on the judgment result of the driving state judging means. And a residual noise detecting means for detecting residual noise at the observation position in the acoustic space, and a noise at the observation position is minimized based on the detection value of the residual noise detecting means and the selection signal of the noise selecting means. And adaptive control means for driving the control sound source.

[Action]

In the invention according to claim (1), the noise generation states of the plurality of noise sources are respectively detected by the noise generation state detection means, and each of the detected signals is used as a reference signal, and the reference signal is determined according to the number of control sound sources. It is individually input to the adaptive filter provided as a component and subjected to filtering processing. The outputs of the plurality of adaptive filters are added by the control sound source driving means for each control sound source and supplied to the control sound source, so that the control sound source generates a control sound based on the driving command. In parallel with this, the driving condition of the vehicle is judged by the driving condition judging means, and the most dominant noise is selected by the noise selecting means based on this judgment information. Therefore, the adaptive control unit controls the adaptive filter so that the noise at the observation position is minimized based on the detection signal of the noise generation state detection unit corresponding to the noise selected by the noise selection unit and the detection value of the residual noise detection signal. To do. As a result, even if there are a plurality of noise sources, the dominant noise at the observation position is accurately reduced by the interference with the control sound.

Further, in the invention according to claim (2), the signals relating to the noise generation state of the plurality of noise sources are individually detected by the plurality of noise generation state detection means, and the driving state of the vehicle or the like is determined by the driving state determination means. . Then, based on the judgment result of the operating state judging means, the noise selecting means selects the detection signal corresponding to the most dominant noise from the detection signals of the plurality of noise generating state detecting means. Therefore, the adaptive control means drives the control sound source so that the noise at the observation position is minimized based on the detection value of the residual noise detection means and the detection signal of the noise selection means. Therefore, a predominant noise is selected in advance and signal processing is performed, so that a simplified configuration is sufficient.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. In this embodiment, a vehicle is used as a power generation device, and the present invention is applied to this vehicle.

In FIG. 1, 2a to 2d are wheels, 4 is an engine, 6 is a vehicle interior as a closed space, 8f and 8r are front and rear seats in the vehicle interior 6, and 9 is mounted on the vehicle. 1 shows an active noise control device.

The active noise control device 9 includes a crank angle sensor 10, vibration pickups 12a to 12d, and microphones 13a and 13b as noise generation state detecting means, microphones 14a to 14h as residual noise detecting means, and a vehicle speed for detecting a vehicle speed. Sensor 15
And a processor unit 16 for signal processing, and loudspeakers 18a to 18d as control sound sources.

To explain this in detail below, the engine 4 is provided with a crank angle sensor 10 that outputs a crank angle signal x ₁ according to the engine rotation. Further, the predetermined position of the suspension member for suspending a wheel 2a~2d the vibration pickup 12a for outputting the road noise signal x ₂ ~x ₅ comprising an electrical signal corresponding to the vibration of the suspension caused by the unevenness of the load
~ 12d is provided. On both sides of the door mirror, a microphone 13a for detecting a sound pressure signal x _6, x ₇ comprising an electric signal wind noise, 13b are provided. Furthermore, when the occupant sits on the seats 8f, 8r in the passenger compartment 6, a total of eight microphones 14 are provided for each occupant's binaural position.
a to 14h are attached, and each of the microphones 14a to 14h is a noise signal that is an electrical signal corresponding to the sound pressure at the ear position.
to detect the e ₁ ~e _8. Further, the vehicle speed sensor 15 detects a signal V corresponding to the vehicle speed.

The crank angle sensor 10 and the vibration pickup 12a-
12d, microphones 13a, 13b, 14a to 14h, and vehicle speed sensor 15
The output end of is connected to the processor unit 16 installed at a predetermined position of the vehicle body, and each detection signal is input to the unit 16.

The output side of the processor unit 16 is individually connected to a total of four loudspeakers 18a to 18d. The loudspeakers 18a-18d are located on the front and rear seats on both sides of the vehicle body.
Two pieces are arranged so as to face 8f and 8r.

As shown in FIG. 2, the processor unit 16 processes the crank angle signal x ₁ , the road noise signals x _{2 to} x ₅ and the sound pressure signals x ₆ and x ₇ which are input to process the loudspeakers 18a to 18d.
To the first processing unit 19A for driving, and the input crank angle signal x ₁ , road noise signals x _{2 to} x ₅ , sound pressure signals x ₆ , x ₇ , noise signals e _{1 to} e ₈ and vehicle speed signal V. Based on the first processing unit 19A
And a second processing unit 19B for controlling the processing by.

The first processing unit 19A includes A / D converters 20A to 20 for A / D conversion.
G, adaptive filters 22A _{u to} 22D _u (u = 1) for performing convolution processing
~ 7), D / A converter 24A _{u to} 24D _u (u = 1 to D / A converter for performing D / A conversion
7), and adders 26A _{u to} 26D _u (u = 1 to 1) for signal addition
6) and are provided. More specifically, the crank angle signal x ₁ , the road noise signal x ₂ , ..., x ₅ and the sound pressure signal are respectively input to the A / D converters 20A to 20G on the input side.
The output side of the 20A~20G leads the individual to the adaptive filter 22A _u ~22D _u branch to one input and one output to four for each signal system (u = 1~7). The output sides of the respective adaptive filters 22A _{u to} 22D _u (u = 1 to 7) are respectively D / A converters 24A _{u to} 24D _u (u = 1 to 7).
Connected to adders 26A _{u to} 26D _u (u = 1 to 6). At this time, among the outputs of the D / A converters 24A _{u to} 24D _u (u = 1 to 7), the first conversion outputs of the respective signal systems are the adders.
26A ₁ , 26A ₂ , 26A ₃ , 26A ₄ , 26A ₅ and 26A ₆ are sequentially added, and the addition output reaches the first loudspeaker 18a. Second to fourth conversion output to each other they are added together by the adder _{26B 1 ~26B 6, 26C 1 ~26C} 6, 26D 1 ~26D 6 In the same manner, each lead loud speakers 18b, 18c, to 18d.

Here, instead of using the D / A converter 24A _u ~24D _u, the adder 26A _u ~26D _u and digitally, so as to provide one at a time of D / A converters for each loudspeaker in a subsequent stage May be.

In addition, the second processing unit 19B receives the noise signals e _{1 to} e _{1 to be} input.
A / D converters 28A to 28H for A / D converting ₈ and A / D for vehicle speed signal V
An A / D converter 29 for conversion, a digital filter 30 for inputting the converted output of the A / D converter 28A / _28H to calculate a filtered reference value r _Lmk described later, and the output of this filter 30.
r _Lmk and the conversion outputs of the A / D converters 20A to 20G, 29 are used to perform necessary operations described below, and the adaptive filter 22A _u ~
22D _u (u = 1 to 7) for updating the microprocessor 31.

Of these, the digital filter 30 inputs each reference signal x _{1 to} x _7, and inputs the microphones 14a to 14h and the speakers 18a to 18d.
The filtered reference signal r _Lmk according to the transfer function between
(See (4) and (5) equations described later) is generated. In the present embodiment, the microprocessor 31 is configured by mounting a microcomputer, performs the processing of FIG. 3 to determine the driving state of the vehicle, and uses the equation (5) described later to use the LMS algorithm belonging to the steepest descent method. The coefficient update calculation is performed based on and the control signal is applied according to the calculation result.
22A _{u to} 22D _u (u = 1 to 7) are supplied to the respective control ends. Therefore, the adaptive filters 22A _{u to} 22D _u (u = 1 to 7) supplied with the control signal change their coefficients in accordance with the calculated values of the microprocessor 31.

 Here, the control principle according to the present invention will be described.

Now, the noise signal detected by the l-th microphone
e _L (n), the noise signal detected by the l-th microphone when there is no control sound (cancellation sound) from the loudspeaker e _PL (n), between the m-th loudspeaker and the l-th microphone Of the j-th (j = 0,1,2, ..., I _C -1) coefficient of the transfer function (FIR (Finite Impulse Response) function) of C
_Lmj , crank angle sensor, vibration pickup, and kth reference signal x from wind noise detection microphone
_k (n), k-th reference signal x _k (n) is input, and the i-th (i =) of the adaptive filter which drives the m-th loudspeaker
If the coefficient of 0,1,2, ..., I _k −1) is W _mki , Is established. Here, the terms with (n) are all sample values at the sampling time n, L is the number of residual noise detection microphones (8 in this embodiment), and M is the number of loudspeakers (this is 4) in the embodiment, K is the number of input channels from the crank angle sensor, the vibration pickup, and the microphone for wind noise detection (7 in this embodiment), Ic
Is the number of taps (filter order) of the transfer function C _Lm expressed by the FIR digital filter, and Ik is the number of taps of the adaptive filter W _mk (may change depending on k).

In the above formula (1), “Σ W _mki · x _k (n−j−
i)} ”(= y _mk ) represents the output when the signal x _k is input to the adaptive filter W _mk , and“ {Σ Σ W _mki · x _k (n−
The term “t−i)}” (= y _m ) represents the sum of the signals input to the m-th speaker, and is expressed as “ΣC _Lmj · Σ Σ W _mki · x”.
_k (n−j−i)} ”, the signal energy input to the mth speaker is output as acoustic energy from the speaker and reaches the 1st microphone via the transfer function C _Lm in the passenger compartment 6. Represents the signal when the
The entire right side of “C _Lmj · {Σ Σ W _mki · x _k (n−j−i)}” reaches the l-th microphone because the arrival signals to the l-th microphone are added to all the speakers. Represents the sum of secondary sounds.

Next, the evaluation function (variable to be minimized) Je is far. Here, γ _L is a weighting coefficient for each microphone 14, and by increasing or decreasing the coefficient γ _L , it becomes possible to change the importance of the noise level at the microphone position.

Then, in order to obtain the filter coefficient W _mk that minimizes the evaluation function Je, the LMS algorithm is adopted in this embodiment. That is, the filter coefficient W _mki is updated with a value obtained by _performing partial differentiation of the evaluation function Je with respect to each filter coefficient W _mki .

Therefore, from equation (2), From equation (1), Therefore, if the right side of the equation (4) is set to r _Lmk (n−i), the filter coefficient rewriting equation can be obtained by the following equation (5).

Here, α is a convergence coefficient and is involved in the speed at which the filter converges optimally and the stability at that time. Although the convergence coefficient α is treated as one constant in this embodiment,
It is possible to use a different convergence coefficient (α _mki ) for each filter coefficient, or it is possible to calculate as a coefficient (α _L ) that also incorporates the weighting coefficient γ _L.

In the above configuration, A / D converters 20A to 20G, 28a to 28h and the digital filter 30, the microprocessor 31 constitutes the adaptive control unit, D / A converters 24A _u ~24D _{u (u} = 1~
7) and the adders 26A _{u to} 26D _u (u = 1 to 6) constitute the control sound source driving means.

 Next, the operation of this embodiment will be described.

First, the microprocessor 31 sets a predetermined time (for example, 20
The processing of FIG. 3 which is executed as a timer interrupt processing of (msec) will be described.

In the step shown in the figure, the microprocessor 31 is the A / D
The vehicle speed signal V input via the converter 29 is input and the value is stored. Next, the process proceeds to step, and the rate of change of the vehicle speed V is calculated based on the read value in the step related to the current interrupt processing and the read value in the step related to the interrupt processing a predetermined number of times before. Then, the process proceeds to the step, and ||>
₀ ( ₀ is a predetermined threshold value capable of discriminating the rapid acceleration / deceleration state) is determined. This determination is to detect a sudden acceleration state. If “NO”, it means that the vehicle is in a rapid acceleration state, and the engine noise control in this rapid acceleration state is prioritized, so that the process proceeds to step. In step, a command for giving priority to engine noise control is issued. Note that the engine speed may be read in place of the vehicle speed V in step.

On the other hand, if “YES” in the above step, it is determined that the vehicle is not in the rapid acceleration state, and the process proceeds to the determination in the step. This determination is made based on whether or not the vehicle speed V read in the step is V> V ₀ (V ₀ is a predetermined threshold value capable of discriminating between high speed and low speed).
In the case of "YES", it is determined that the vehicle is traveling at high speed and the process proceeds to step. In step, a command for giving priority to wind noise control is issued.

Further, in the case of "NO" in the above step, it is determined that the vehicle is not in the rapid acceleration state or in the high speed traveling state, the process proceeds to the step, and a command for giving priority to road noise control is issued.

In the present embodiment, the vehicle speed sensor 15, the A / D converter 29, and the processes of steps 1 to 3 in FIG. 3 correspond to the driving state determining means, and the processes of steps 1 and 2 in FIG. 3 correspond to the noise selecting means. There is.

 Next, the overall operation will be described.

When the vehicle travels, the rotational vibration of the engine 4 is transmitted to the vehicle interior 6 via the vehicle body and remains as a muffled sound in the vehicle interior 6. The engine rotation state at this time is determined by the crank angle sensor.
The crank angle signal x ₁ detected by 10 and corresponding to the rotation speed of the engine 4 is output to the processor unit 16. In parallel with this, the suspension member vibrates when the road surface is uneven during traveling. As a result, the vibration state is detected by the vibration pickups 12a to 12d, and the road noise signal corresponding to the vibration input from the road surface is detected.
x _{2 to} x ₅ are output to the processor unit 16. Also,
Microphones 13a, 13b outputs a sound pressure signal x _6, x ₇ corresponding to the wind noise in the vicinity of the door mirror to the processor unit 16. Further, the vehicle speed sensor 15 outputs a signal V corresponding to the vehicle speed to the processor unit 16.

Then, within the processor unit 16, the detection signal x ₁
.About.x ₇ are converted into digital values by the A / D converters 20A to 20G, and then supplied to the adaptive filters 22A _{u to} 22D _u (u = 1 to 5) and the microprocessor 31, respectively. The vehicle speed signal V is also supplied to the microprocessor 31 via the A / D converter 29.

Further, the microphone 14a~14h detects the sound remaining in its installation position (observation position), and outputs the noise signal e ₁ to e ₈ similarly processor unit 16 in response thereto.
Then, within the processor unit 16, the noise signal e ₁
To e ₈ is converted into a digital amount by the A / D converter 28a to 28h, are respectively supplied to the digital filter 30.

The digital filter 30 sends the filtered reference signal r _Lmk to the microprocessor 31 based on the equation (4) from the value of the input signal. Microprocessor 31
Is an update calculation of the filter coefficient of the adaptive filter which is inputting the reference signal for which the priority command is issued at that time, based on the equation (5) using each input value. Do not update. That is, for the update, the evaluation coefficient, that is, the noise signal e corresponding to the residual sound pressure from each of the microphones 14a to 14h is added to the filter coefficient W _mki (n) at the current sampling time n.
The filter coefficient in the direction in which the sum of squares of _L (n) is minimized is applied to each filter, and the filter coefficient W _mki (n + 1) to be set at the sampling time (n + 1) is obtained. The microprocessor 31 then calculates the calculated value W _mki.
The control signal corresponding to (n + 1) is individually output to the adaptive filter. Therefore, the filter coefficient in each of the corresponding adaptive filters is as follows at the sampling time (n + 1):
The newly calculated filter coefficient W _mki is updated.

As a result, specifically, when the engine noise priority control in the sudden acceleration state is commanded in the processing of FIG. 3, four adaptive filters for inputting the crank angle signal x ₁ are input.
The coefficients of only 22A _{1 to} 22D ₁ are updated at appropriate timings that do not hinder the filter processing, and other filters are not updated. Further, in the processing of FIG. 3, when the wind noise priority control at high speed is instructed, the sound pressure signals x ₆ and x ₇
8 adaptive filters 22A _{6 to} 22D ₆ and 22A _{7 to} 22D ₇
Only the coefficient is updated accordingly. Furthermore, if similar road noise priority control is instructed, the road noise signal
16 adaptive filters 22A _{2 to} 22D ₂ and 22A _{3 to} 22D for x _{2 to} x ₅
Only the coefficients of ₃ , 22A _{4 to} 22D ₄ and 22A _{5 to} 22D ₅ are updated.
Any of the above update controls is repeated at every predetermined timing so as to minimize the evaluation function Je.

On the other hand, in each of the adaptive filters 22A _{u to} 22D _u (u = 1 to 7), according to the filter coefficient set at that time,
A convolution operation of the input signals x _{1 to} x ₇ and the coefficient W _mki is performed to obtain the pressure y _mk (n). This adaptive filter 22A _{u to} 22D _u
The outputs of (u = 1 to 7) are added to the adders 26A _{u to} 26D _u (u = 1
~ 6), output signal y for each speaker drive system
_mk (n) are added, the sum y _m (n) is calculated, and the sum signal y _m (n) is the first to fourth speakers 18a~1
Output to 8d respectively.

As a result, each of the speakers 18a to 18d receives the input signal y
Generates a control sound (secondary sound) according to _m (n). That is, the control sound having a phase that cancels the residual noise at the eight observation points (microphone installation positions) is generated by the speaker 18a.
~ 18d, the control sound propagates in the vehicle interior space corresponding to the transfer function C _Lm estimated in advance based on the directivity of the speaker.

Therefore, in the rapid acceleration state in this embodiment, the vehicle interior 6
The engine noise, which increases due to a sudden change in the engine driving condition, becomes the dominant noise in the passenger compartment 6,
According to this embodiment, the control sounds for canceling the engine are generated from the speakers 18a to 18d, and the dominant noise is extinguished. Further, in the high-speed traveling state, the increasing wind noise is dominant, but this wind noise is surely reduced by the control sound. Furthermore, in cases other than sudden acceleration and high speed running, road noise is dominant, but the noise is reduced.

In this way, at the observation points by the microphones 14a to 14h and their surroundings, the most predominant vehicle interior noise at that time is appropriately canceled according to the driving situation of the vehicle, and the noise heard by the occupants is reduced. There is. As a result, the microprocessor 31 does not have to update the coefficients of all the 28 adaptive filters 22A _{u to} 22D _u (u = 1 to 7) at every sampling, and in the present embodiment, a maximum of 16 priority commands are issued. Update the filter coefficient of. Therefore, the microprocessor 31
There is also an advantage that the calculation load can be reduced, high-speed calculation is not always required, and the cost can be reduced.

Next, another embodiment of the present invention is shown in FIG. In the figure, the same components as those in FIGS. 1 to 3 are designated by the same reference numerals, and the description thereof will be omitted.

The embodiment shown in FIG. 4 is also carried out on a vehicle in the same manner as the above-mentioned embodiment, and the detection signals x _{1 to} x ₇ of the crank angle sensor 10, the vibration pickups 12a to 12d, and the wind noise microphones 13a and 13b are In the processor unit 16, it is input to the selection circuit 50 as noise selection means. The selection circuit 50 receives the selection signal SL from the microprocessor 31 and selects a reference signal x _C selected from the detection signals x _{1 to} x _7.
(C = 1, 2, ...) Is input to the four adaptive filters 54a to 54d via the A / D converter 52. Microprocessor 31 also has performed the processing shown in FIG. 3, is a detection signal x ₁ ~x ₇ of any of the sensors so as to output a selection signal SL in response to whether to preferentially selected. In the figure, 56a to 56d are D / A converters, 58a to 58d are loudspeakers, and other embodiments are the same as the above-mentioned embodiments.

Therefore, in the embodiment according to the configuration shown in FIG. 4, in addition to the same effects as the above-described embodiment, the detected sensor signals x _{1 to} x ₇ are prioritized based on the vehicle running state at that time. Accordingly, the number of adaptive filters and each circuit on the input / output side thereof can be significantly reduced, and the configuration can be simplified because the adaptive signal processing is performed in a state selected in advance. Further, unlike the above-described embodiment, since the control sound is not generated from the adaptive filter that does not update the coefficient, there is an advantage that the noise reduction is performed with higher accuracy.

In the above embodiment, the case where the loudspeaker as the control sound source and the plurality of microphones as the residual noise detecting means are provided respectively has been described, but the active noise control device of the present invention is not necessarily limited to this. For example, the number of loudspeakers may be one.

Further, the active noise control device of the present invention is not limited to the device applied to the passenger compartment of the vehicle as in the above-described embodiment, and may be a device applied to the cabin of an aircraft, for example. The device may be configured to reduce the indoor noise caused by the rotation of the outdoor unit for air conditioning. On the other hand, in the above-described embodiment, the case where the plurality of noise sources exist outside the kind of closed space called the vehicle interior has been described, but in the present invention, the noise sources are installed inside such a closed space. It can also be applied in cases.

Further, in the above-described embodiment, as the detection contents of the plurality of noise generation state detecting means, a muffled sound caused by engine vibration, a crank angle signal correlated with exhaust noise, a pickup signal of suspension vibration correlated with road noise, And the configuration using the microphone signal correlated with the wind noise is described, the present invention is not limited to these description contents. For example, a pickup signal for a case of a differential gear or a case of a transmission (a case of a driving force transmission system). A signal that correlates with noise caused by vibration) and a pulse signal that corresponds to the rotation of the output shaft of the transmission for vehicle speed measurement (a signal that correlates with noise due to meshing of the transmission and the differential gear) are also included. Can be a channel or these Or a combination of any of the.

Furthermore, the algorithm for updating the filter coefficient of the present invention is the time domain LM as described in the above embodiment.
The present invention is not limited to the S (Least Mean Square) algorithm, and may be, for example, the frequency domain LMS algorithm.

〔The invention's effect〕

As described above, according to the invention of claim (1), while individually detecting the signals relating to the noise generation state of the plurality of noise sources, the operating state of the power generation device is determined, and based on this determination result The most dominant noise is selected from the noises caused by a plurality of noise sources, and the adaptive filter is based on the detection signal of the noise generation state detection means and the detection value of the residual noise detection means corresponding to the selected noise. Unlike the conventional device, since the adaptive signal processing is performed, even if there are multiple noise sources, the noise that seems to be most dominantly generated in the acoustic space at the time of control is preferentially turned off. As a result, it is possible to effectively reduce noise in the acoustic space such as the vehicle compartment.

According to the invention as set forth in claim (2), a plurality of noise generation state detection signals are detected based on the determination result of the operating state of the power generation device after individually detecting the signals regarding the noise generation states of the plurality of noise sources. The detection signal corresponding to the most dominant noise source is selected from among the above, and the adaptive signal processing is performed based on the selected detection signal and the residual noise detection signal. In addition to the same effect as the effect, there is an effect that the configuration of a filter or the like relating to the adaptive signal processing can be minimized and the configuration can be simplified.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram in which the processor unit in the embodiment of FIG. 1 is partially omitted, and FIG. 3 is implemented by the microprocessor of FIG. FIG. 4 is a block diagram showing a partial configuration of a processor unit according to another embodiment of the present invention. 9 is an active noise control device, 10 is a crank angle sensor, 12a
~ 12d is a vibration pickup, 13a and 13b are microphones, 14
a to 14h are microphones, 16 are processor units, 18
a-18d, 58a-58d are loudspeakers, 20A-20G, 28A-2
8H, 29, 52 are A / D converters, 22A _{u to} 22D _u (u = 1 to 7), 54a
˜54d is an adaptive filter, 24A _u ˜24D _u (u = 1 to 7), 56a
~56d the D / A _{converter, 26A u ~26D u (u =} 1~6) are adders, 30 is a digital filter, the 31 microprocessor, 50 a selection circuit.

Claims (2)

(57) [Claims] 1. An active noise control device for reducing a noise by generating a control sound from a control sound source in an acoustic space where noises are transmitted from a plurality of noise sources having no correlation with each other. A plurality of noise generation state detecting means for individually detecting a signal relating to the noise generation state of the noise source, and at least the number of control sound sources for each of the detection signals of the plurality of noise generation state detection means, and An adaptive filter for individually inputting detection signals, and a control sound source driving means for adding each output of the plurality of adaptive filters to each control sound source and supplying the control sound source, and at an observation position in the acoustic space Residual noise detecting means for detecting residual noise, operating state determining means for determining operating state, and the plurality of noise sources based on the determination result of the operating state determining means Noise selecting means for selecting the most dominant noise among the noises transmitted from the noise detecting means, the detection signal of the noise generation state detecting means corresponding to the noise selected by the noise selecting means, and the detection value of the residual noise detecting means. And an adaptive control means for controlling the adaptive filter so that the noise at the observation position is minimized. 2. An active noise control device for reducing a noise by generating a control sound from a control sound source in an acoustic space in which noise is transmitted from a plurality of noise sources having no correlation with each other. Noise generating state detecting means for individually detecting signals relating to the noise generating state of the noise source, operating state determining means for determining the operating state, and the plurality of noise generating states based on the determination result of the operating state determining means. Noise selection means for selecting a detection signal corresponding to the most dominant noise from the detection signals of the detection means, residual noise detection means for detecting residual noise at the observation position in the acoustic space, and residual noise detection means And an adaptive control means for driving the control sound source so that the noise at the observation position is minimized based on the detection value of the noise and the selection signal of the noise selection means. Active noise control device to be a characteristic.